Art of bating hides and skins



Patented Feb. 1 3, 1940 PATENT OFFICE ART or BATIYNG HIDES AND SKINS has Pfannmuller, North Plainfield, N. J., as-

signor to Wallerstein Company, Inc., New York, 1 N, Y., a corporation of New York No Drawing. Application May 6, 1937,

:- Serial-No. 141,096

into commercial leather they are subjected to a number of processes; For example, after the hides or skins have been flayed, cured and soaked,

they are treated'for dehairing. -.This treatment loosens the hair so that it can easily, be removed. One of the common methods of treatmentfor 10 loosening hair consists in 'soakingtheskins or hides in a lime solution, either with'or without the .addition of sulfides, red arsenic or other chemicals. It has also been proposed to effect the loosening of the hair by, certain enzymatic 15 methods, such use 'of enzymes being. usually carriedout after theskins" havebeen'first subjected to an alkaline bath. After the hides or' skins have been subjected to the lime or alkaline proc-' ess, they are usually .partly'neutralized. As a result of the limetreatment, the fibres of the hides or skins have more or less resilience or elasticity and the presence of limeor soda, in'the form of free alkali or alkalineisalts, causes'a swelling of the hides or skins. Before thehides or skins can be tanned, they must be brought downor reduced, particularly in the production of light and soft leather," in order to remove this elastic or resilient condition, render the hides or skins soft, supply andv flaccid," and to y remove the alkalineswelling'.x To this end, the

hides or skins are subjected to a process'known as deliming or bating or puering. Thisprocess normally consists in ,neutralizing? the hides .or

skins to, a pH ranging from slight acidity. to

aboutlO, ordinarily in thepresence of proteolytic enzymes, I This neutralizing or lessening of alkalinity may be achieved in various ways. For examplait has. been proposed to use inorganic acids suchas 4 sulfuric, hydrochloric and boric acids and organic acids such as lactic, formic, acetic and 'butyric' acids. The result of such treatment is the removal from the hides orskins of a large amount manure. mentation, with the formation of various acids,

I more particularly large amounts" of C0 The deliming process is usually, though not I necessarily, carried out in the presenceof pro- ,teolytic enzymes which act on certain constit- 3 uentsof thev hides or. skins. The enzymesor 55' enzymatic products used. for this purpose may be derived from various sources, such, for example, as pancreas glands or from preparations which containthe proteases of various plants or molds I or other micro-organisms, e. g., bacterial proteases. "They may, of course, be generated by 5 micro-organisms during the above .mentioned process of fermentation. 1 While this neutralizing process is necessary, not onlyfor'the purposes mentioned but also because the presence of the lime in the hides or- 10 skins is undesirable in subsequent operations, it has been found that when the hides and skins are subsequently treated with acids, as in the tanning process," the otherwise harsh action of the acids is somewhat mitigated if there is prescut one Or more relatively insoluble salts of a basic nature; While the fermenting process just referred to results in a large part of the lime being retained in the form of such a'salt, namely,

calcium carbonate, the advantages of its pres- 2 ence are far outweighed by the disadvantages incident to the fermentation process itself, .In fact, 1 becausethe fermentation method of hating is so objectionable, for a variety of reasons, it has, to a large extent, been replaced in commercial prac- 25 vide a bate and a method of bating hides and skins that results in the presence therein of one or more relatively insoluble salts of a basic nature and that, at the same time, avoids the objection- 4 able features of the methods above referred to.

i Other objects and advantages of the invention will be apparent from the ensuing description.

According to the present invention, 1 use as a bating agent for offsetting or neutralizing. the

alkalinity of the lime and soda, one or more salts "of ammonia that will react with the lime to form relatively insoluble salts of a basic nature. For this purpose I have found that the carbonates,

bicarbonates and carbamates of ammonia are suitable and satisfactory. Such salts react with thelime to form relatively insoluble calcium carbonates, with'the result that, While the alkalinity of. the lime is offset or neutralized, so that the skinsare properly bated, lime is retained in the skins in the form of relatively-insoluble salts of a basic nature. That is, the advantages of the old fermentation process are retained but thedangers and disadvantages of fermentation are avoided. Not only is no forced fermentation necessary but any incidental fermentation that might naturally occur can be prevented since'the bating operation may be carried out in the presence of disinfectants. Moreover, by controlling the amount of ammonium salts used, it is possible to control the extent to which the swelling is reduced and the extent to which the lime, in the form referred to, is retained.

Depending on the desired amount of retained calcium salts, the ammonium carbonates, bicarbonates or carbamates may be used alone or in connection with other deliming agents, such as various acids, organic or inorganic, for example,

sulfuric, hydrochloric, acetic, formic and carbonic acids, or other ammonium salts such as chlorides and sulfates. These other neutraliziing agents may be added either simultaneously with the ammonium carbonates, bicarbonates or carbamates or before or after the addition of the latter.

It is not essential to add the ammonium carbonates, bicarbonates or carbamates as such, since such salts may be generated during the process. For example, the desired ammonium salt or salts may be obtained by adding am 'monia and CO2; or by adding ammonium salts,

salts, such as chlorides, for example there is formed, by reaction, ammonium carbonate or bicarbonate and sodium chloride. During the action of ammonium carbonates,

bicarbonates or carbamates onlimed skins, am'

monia is driven off. If it is desired to neutralize this ammonia, it may be accomplished by adding an acid, preferably-a weak acid such as vboric or carbonic or a Weak organic acid, such as amino acids, or acid salts such as ammonium or sodium bisulfates or bisulfites. If the above salts or stronger acids are used they should be added after the main action of the ammonium carbonates, bicarbonates or carbamates is over but if weak acids are used they may, if desired, be added simultaneously with the ammonium salts themselves.

The formed ammonium may also be removed to a considerable extent by expelling it by mechanical treatment in a more or less open vessel, such, for example, as a paddle, at a temperature of F. or more.

In carrying out the invention to what is now considered the, best advantage, the calcium cara bonate or other calcium salt should be precipi tated in an amorphous form. This can be at-- tained by keeping the pH on the alkaline side,

I. about "7.0 or higher, during the whole bating procedure. I have also found that it is advantageous to use small amounts of phosphates in the bating liquor, for example, from 2% to 60% of the ammonium carbonates, bicarbonates or. carbamates used. The presence of magnesium salts also aids in the formation of amorphous calcium carbonate, etc. I used in the alkaline beamhouse process was de- While sodium bicarbonate has previously ficient in magnesium oxide, magnesium saltsmay be added.

The ammonium carbonates, bicarbonates or Therefore, .if the limo carbamates, with or Without the other ammonium salts or the acids above mentioned, may

also be used in combination with proteolyticj I enzymes or enzymatic products derived from var ious sources, for example, pancreas glands or r preparations containing the proteasesof vari ous plants or molds, or other micro-organisms, for example,-bacterial proteases. If the enzyme preparations are used in a-dry. precipitate or are absorbed on wood flour, etc.,a dry hating compound may be obtained by mixing such enwith or without other ammonium'salts cr -with or without acids, such as boric or amino acids, in a dry form, or with or without salts ofv phoszymatic preparations in a dry state with am- 5 monium carbonates, bicarbonates or carbamates,

phoric acid, such as di-ammonium mono-phosr phate or mono-ammonium di-phosphate.-

While the amounts of materials andth e con ditions under which they are used may vary widely, I have-found the procedure set forth I in the following examples to give satisfactory results, producing leather of superior and improved quality. 1

of hides or skins is to be understood to be white Weigh), i. .e., weight after dehairing and flesh-- ing. It is also tobe understood that the basis. of the bating liquor is water, the amount used.

varying as desired. The usual range is-from one part water to twoto five parts hides or skins by weight.

Where a disinfectant. is specified, any suitable closed in U. S. Patent 1,985,267. 9

disinfectant may be used, for example, those dis '5 Where enzyme preparations absorbed on Wood v flour are specified, itis to be understood that the weight given includes both-,the absorbed and the absorbing material.

0 Example 1 Subject: kipskins to a lime solution sharpened with 'sodiumsulphide forabout four days." Take out skins and unh'air'and flesh thesame ac-F' N For 3450 pounds cording to known practice.

of these skins, add to the bating liquor about four pounds of an enzyme preparation of bac--- terial' origin, about'one pound ammonium bicarbonate and about twenty-two pounds emmonium sulfate. Subject the skins to a bating treatment in such liquor at about 92 F. for about one'hour'. Finish the skins for chrome leather in usual known manner. 7

v Example 2 j Soak; and unhair wet 'sal tedlndia skins in customary lime bath. After unhairing andflesh ing,' -wash with water-for a bout15 minutes. For. 2000 pounds of skim, add to the batingiliquor about ten pounds of proteolytic enzyme prepa-g ration and abouttwenty'pounds of a mixture, consisting of about 33% ammonium carbonate,

about 66% ammonium sulfate and. about four.

pounds disinfectant. Bate overnight in a paddle atiabout 94 F. I Examp e 3 i Soak goatskins as usual and subject to an alkaline swelling bath containing both lime and 0 In the examples here given, the specified weight j mono-phophate.

the. skins andsubject'the same to an unhairing bath containing, bacterialproteases. Unhair and fleshin usual manner. For 1000 pounds of skins, add to the bating liquor about ten pounds, of a bating preparation comprising about 75% ofya proteolytic enzyme absorbed on wood flour and about 25% ammonium carbonate. -Add a disin iectant. Bateovernight at. about 90 F.

.. Example 4' Soak and unhair. goatskins in customary lime bath. After unhairing and fleshing, bate 1000 pounds of skins overnight in a bating liquor to which has been added seven and one-half pounds of an enzyme preparation and about twenty-two and one-half pounds of a mixture containing about 80% ammoniumcarbonate, about 10% ammonium sulfate and about 10% urea by weight. Bate overnight at about 88 F.

Example 5 For the added batingmaterial of Example 4, substitute about five pounds of a pancreatic bating preparation and about twenty-five pounds oi a mixture consisting of about 60% ammonium chloride and about 40% sodium bicarbonate. Bate at 82 F. to 96 F.

Example 6 Example 7 For the added bating material of Example 4, substitute about five pounds of a proteolytic enzyme preparation absorbed on wood flour and about fifteen pounds of a mixture consisting of about 42% sodium bicarbonate, about 54% ammonium chlorideand about 4% di-ammonium Bate at 82 F. to 96 F.

Example 8 Soak and unhair goatskins in customary lime bath. Afterlunhairing and fleshing, bate 2000 about sixteen pounds of a mixture consisting of about equal amounts by weight of a pancreatic enzyme absorbed on Wood flour and ammonium bicarbonate. Bate about four hours at about F. J a a a Example 9 I Soak and unhair goatskins in thecustomary lime bath. After unhairing and fieshing, treat 2000pounds of skins overnight in a liquor to which has been added about ten pounds ammonium bicarbonate.

What is claimed is: I p 1. The process of bating hides and skins which comprises subjecting limedhides or skins to a I [comprises subjecting limed hides 0r skins to a bating material containing an enzymatic preparation and an ammonium salt which will form,

by reaction. with the lime inthe hides' or skins,

a relatively insoluble salt of a basic nature.

3. The process of bating hides and skins which comprises subjecting limed hides or skins to a ,bating material containing an enzymatic preparation, at least. one reagent tending to react withfipartbf the lime in the hides or skins to form soluble salts, and also containing an am-' 'monium salt which will form, by reaction with part of the lime,a relatively, insoluble salt of a basic nature.

4. The process of bating hides and skins which comprises subjecting limed skins or hides to a bating liquor to which has been added two ammonium salts, one of which forms, by reaction with the lime in the hides orskins, a relatively soluble calcium salt and the other of which'forms,

'by reaction with the lime, a relatively insoluble calcium saltof a basic nature. I

5. The process of bating hides and skins which comprises subjecting limed hides or skins'to a bating material containing an ammonium salt which. will form, by reaction with the lime in the hidesor skins, a relatively insoluble salt of a basic nature, the bating material also containing a phosphate.

6. A bating liquor for bating hides orskins comprising at least one reagent tending to react with the lime in the hides or skins to form soluble salts and'at least one ammonium salt which will form, by reactionwith the lime, a relatively insoluble salt of a basic nature.

7. A bating liquor for bating hides or skins comprising an enzymatic preparation and an ammonium salt which will form, by reaction with the lime in the hides or skins, a relatively insoluble salt of a basic nature. I

8. A dry material for use in a bating liquor and which comprises a mixture of an enzymatic preparation and an ammonium salt selected from the group consisting of carbonates, bicarbonates and carbamates. I 9. The process of bating hides and skins which comprises subjecting limed hides and skins to.

a bating material containing an ammonium salt which will form, by reaction with the lime in the hides or skins, a relatively insoluble salt of a basic nature, the bating material also contain-.

ing a magnesium salt. l

10. A composition of matter in dry form, for use in a bating liquor and comprising a mixture of anenzymatic preparation, an ammonium salt which, in the liquor, will tend to form, by reac-. tion with lime, a relatively insoluble salt of a basic nature, anda substance which, in the bath,

will tend toreact with lime to form soluble salts.

11. A composition of matter, in dry form, for

use in a bating liquor and comprising a mixture vof an enzymatic preparation, an ammonium salt which, in the liquor, will tend to form, by reactionwith lime,a relatively insoluble salt of a basic nature, asubstance which, in the bath, will tend to react with lime to form soluble salts, and a phosphate. f

12. The process of bating hides, and skins which comprises subjecting limed hides or skins to a batingmaterial containing at least one reagent tending to react with part of thelime in the hides or skins to form soluble salts, and also containing an ammonium salt selected from the group consisting of carbonates, bicarbonates and.

carbamates.

13. The process of bating hides and skins.

which comprises subjecting limed hides or skins to a bating material containing an enzymatic with-part of the lime to fornrsoluble' saltsg and-i an ammonium salt selected'from the group conv sisting of' carbonates, 'bicarbonateslgnd TCS/I bainates.

16.L'A dry material for use batingiiquor.

for limed skins and hides, which'comprises a mixture-of an enzymatic preparation and an v ammonium salt which will for-111,: by reaotion with the lime in the-hides or skins; arelatively insoluble salt of a basic nature.

i a JUIJUS PFANNMULLEBJ 

